Kinetic Energy penetrators are very effective in neutralizing incoming air borne threat munitions such as rockets, artillery or mortars, for instance. These penetrators are typically monolithic cylindrical objects that are made from high density materials, to enhance their ability to penetrate and defeat the threat and are spin stabilized in their flight to their target. However, the high kinetic energy and ballistic mass of these penetrators poses a problem in urban environments, because they still possess enough energy to kill bystanders and friendly troops when they return to the ground. This problem restricts the use of an otherwise effective air defense munitions. Other solutions to this problem are self destructing high explosive munitions, which after a preset time in flight detonate, after it has passed its effective operational range. The problem with this class of projectiles is that of dealing with the hazards of cleaning up unexploded ordnance, which occur due to unreliability of the self destruct mechanism. Shown herein is a kinetic energy penetrator for air defense, that self destructs beyond its operational range into fragments that are not lethal to personnel on ground. The penetrator does not use pyrotechnic or energetic materials means to activate the self destruct process. The proposed solutions are mechanisms that still allow the use of dense materials, but effectively reduce collateral damage by fragmenting the penetrator without the use of pyrotechnic means. A full bore projectile structure is shown that is composed of a plurality of axi-symmetric disks stacked on each other. Preferred embodiments include a circular disk with a hole in the center, such that a stack of such disks creates a channel through the axis of the projectile, thus the penetrator structure would be composed of a coaxial stack of axi-symmetric disks. Each disk is sized so that its individual ballistic coefficient ensures that aerodynamic drag (compared hypothetically to the drag if it were the shape of a rod or needle rather than circular) is sufficient to reduce terminal energy to below levels established for lethal injury to ground personnel which is considered to be approximately 75 Joules on impact. Another embodiment utilizes disks which although are not all alike are sized according to ballistic need for improved flight characteristics on a case by case basis. Each disk also retains its stability in flight from the spin imparted to its parent projectile. This ensures that a maximum frontal area of the disk is presented to the air stream for the remainder of the flight, ensuring maximum drag and therefore minimal terminal energy. Each disk is separated from succeeding disks on each side by a spring mechanism that enables separation after the separation process is initiated in flight. This is true even if no airborne target is hit by the round. However, if a target is engaged by this round, the respective disks will also separate because the round is almost certain to break apart on impact. Once on the ground, disks pose no explosive ordnance problems. Also, the fact that no pyrotechnic materials are used will reduce logistical burden and therefore also reduce lifecycle costs.